Armored products made of fiber-reinforced composite material with ceramic matrix

ABSTRACT

Protection products and armored products made of a fiber-reinforced composite material with a ceramic matrix, include a protection element for partial or complete absorption of at least one impact-like load focussed at a point. The protection element has a body having at least one dimension at least equal to 3 cm, in a direction perpendicular to a load to be absorbed. The body includes a fiber-reinforced composite material having a ceramic matrix with at least 10% by weight of silicon carbide and having reinforcing fibers. At least 5% by weight of the reinforcing fibers are carbon fibers and/or graphite fibers.

CROSS-REFERENCE TO RELATED APPLICATION

This is a division of U.S. application Ser. No. 09/547,684, filed Apr.12, 2000, now U.S. Pat. No. 6,537,654.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to armored products made of a fiber-reinforced orfiber-bundle-reinforced composite material with a ceramic matrix forpartial or complete absorption of at least one impact-like load focussedat a point.

In the following description and in the claims, both individual fibersand fiber bundles that are used for the most part and can have asubstantially greater width as well as height, as compared withindividual fibers, are referred to together under the term “fibers”.

Fiber-reinforced composite materials with a ceramic matrix have beenknown for a long time and in general are distinguished by high strengthand rigidity with simultaneously low weight. Those properties aremaintained even up to high temperatures. The fiber-reinforced compositematerials have a high thermal conductivity and at the same time a lowthermal expansion and thus an excellent resistance to thermal shocks.

Starting from carbon-fiber-reinforced composite materials with a carbonmatrix (CFC), composite materials with SiC as a matrix have beendeveloped to an increasing extent over the last ten years, with carbonfibers (C/SiC) and silicon carbide fibers (SiC/SiC) being used asreinforcing fibers.

A silicon carbide body which is reinforced with short graphite fibersand which has a quasi-ductile breaking behavior, is known from GermanPublished, Non-Prosecuted Patent Application DE 197 10 105 A1. Thereinforcing short graphite fibers are surrounded by at least one shellof graphitized carbon obtained by impregnation with impregnating agents,which can be carbonized, and subsequent carbonization. The shell of thefibers is partly converted into silicon carbide during the production ofthe C/SiC composite material. To that end, the composite body isinfiltrated with liquid silicon, wherein the at least partial conversionof the carbon matrix of the carbonized initial product into siliconcarbide also takes place.

In the discussion of that prior art, lining materials for reusable spacemissiles, nozzle linings of jet engines, turbine blades or even frictionlinings are generally spoken of as possibilities of use for compositematerials. The composite materials described in German Published,Non-Prosecuted Patent Application DE 197 10 105 A1 can be used asportions of gas turbines, as components of burners and nozzles, ashot-gas pipes, or even as friction materials for high loads, such aslinings for brakes.

A process for producing fiber-reinforced composite ceramics with hightemperature fibers which are reaction-bonded with a matrix based onsilicon and silicon carbide or a silicon alloy, as described in GermanPublished, Non-Prosecuted Patent Application DE 41 27 693 A1, forexample, is known from German Patent DE 197 11 829 C1. Composite bodiesof that type are used for the production of mass-produced components,such as brake discs.

The use of ceramics as an armor plating system, because of their lightweights, is also known. Ceramics are generally distinguished by highrigidity and hardness. In the case of their use for armor plating, it isessential that the ceramics be able to withstand a plastic deformationunder high load. A high tensile strength is required particularly on arear surface of an armor plate. For that reason, a typical armor platingin which a composite comprising ceramic is used is therefore formed of aceramic front side which is provided with a fibrous composite or metalsubstrate as a reinforcement (backing) on its rear side. Usually, thosedifferent materials are connected to each other by gluing. Glass,glass-ceramics, or technical ceramics such as oxides, borides or evencarbides are used as the ceramic material. In particular, aluminum oxidehas distinguished itself because it is also relatively favorable interms of cost. However, the ability to withstand a plastic deformationis not particularly satisfactory in ceramics. Since ceramics display abrittle breaking behavior, a loading of the ceramic material focussed ona point, for example by a projectile, leads to a continuous cracking inthe ceramic material. The ceramic material is therefore destroyed over alarge area and thus loses its protective effect. Heretofore, thatproblem could be remedied only by mounting small ceramic segments havinga maximum extent of 3 cm for a very high protection (protected cars) and10 cm for a simple, for example military, protection, on a backing in aplane perpendicular to an action of the point-focal load. Thus, if aprojectile was impacted, always only one ceramic segment would ever bedestroyed. However, the production of a composite made up of suchceramic segments is very costly. Thus, ceramics alone have notheretofore been able to be used as a large-surface protective element.

When an armor plate is hit by a projectile, in the case of aconventional ceramic material, a breakage of the ceramic plate itselfresults because of a reflection of stress waves within the ceramicplate. It is only because a further rear side, for example made ofmetal, is mounted behind the ceramic plate, that it is possible toprevent the projectile from completely penetrating that armor plate.

In the case of the use of ceramic material for armor plates, it isnecessary for the ceramic material to have a hardness which is clearlygreater than the material of the projectile, which usually has aVicker's hardness of approximately 6.5 to 8.0 kN/mm². It would thereforebe favorable to use materials having a hardness of more thanapproximately 9.8 kN/mm². If the ceramic material is too soft, theprojectile core penetrates through the ceramic material, because it isnot damaged or flattened by the ceramic material.

However, there is also ammunition with a clearly greater hardness,particularly if ammunition having a core of tungsten carbide in anickel-iron matrix is used. In such a case, the hardness can rise toapproximately 11 kN/mm², for example.

A ceramic material made of highly pure aluminum oxide could withstandsuch a projectile because it has a hardness of more than approximately16.6 kN/mm². It is likewise possible to use other ceramic materials, forexample silicon carbide, as already mentioned above, boron carbide, oreven titanium diboride, the hardness of which is clearly greater.

It is likewise known to use zirconia-reinforced aluminum oxide, ortitanium borides. However, a hot-press process has to be used duringproduction in order to obtain the optimal properties. In order to dothat, the powders from the respective starting material are compactedand heated in a graphite nozzle under an inert gas atmosphere. Due tothe complicated production process, the costs of a single armor plateare consequently high.

In view of the price/output ratio, aluminum oxide has heretofore beenconsidered the ceramic material of choice.

In the meantime, first attempts were made to use fiber-reinforcedcomposite materials with a ceramic matrix instead of the conventionalceramics for protection against projectiles. For that purpose, trialswere carried out with SiC/SiC composite materials. They displayedlimited damage to the material by the impacting projectile, so that thematerial provides protection against multiple bombardment from anautomatic weapon (multiple hits). However, the protective effect againstprojectiles is very low in comparison with the known ceramics. (see anarticle by Orsini and Cottenot in the 15th International Symposium onBallistics, Jerusalem, 1995).

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide armored productsmade of a fiber-reinforced composite material with a ceramic matrix,which overcome the hereinafore-mentioned disadvantages of theheretofore-known materials and products of this general type and inwhich the ceramic material has a low specific weight and a goodresistance to bombardment and thereby withstands even a repeatedbombardment. Furthermore, the material which is sought should to be ableto be shaped as a large-surface element through the use of simpleshaping processes. In addition, it is a further object of the inventionto select the material in such a way that it satisfies even high safetydemands with respect to bombardment and other impact-like loads. In thisconnection, the material which is sought should either be the protectiveelement alone or have a conventional rear-side reinforcement.

With the foregoing and other objects in view there is provided, inaccordance with the invention, a protection element for partial orcomplete absorption of at least one impact-like load focussed at apoint, comprising a body having at least one dimension equal to orlarger than 3 cm, preferably 10 cm and particularly preferably 30 cm, ina direction perpendicular to a load to be absorbed; the body including afiber-reinforced composite material, the composite material having aceramic matrix with at least 10% by weight of silicon carbide, and thecomposite material having reinforcing fibers; and at least 5% by weightof the reinforcing fibers being carbon fibers or graphite fibers orcarbon fibers and graphite fibers.

In order to meet the high safety demands with respect to bombardment andother impact-like loads, elements made of a carbon-fiber and/orgraphite-fiber-reinforced composite material with a ceramic matrix arepreferably used. The elements are formed of 40 to 85% by weight siliconcarbide, 5 to 55% by weight carbon and 0 to 30% by weight silicon withrespect to the total weight of the composite material. The fiber portionof the composite material is 5 to 40% by weight of the total weight. Inthis connection, the average fiber length of the reinforcing fibers is0.2 to 15 mm and the fibers are coated with at least one layer ofcarbon. In this connection, the minimum thickness of the elements in thedirection of the action of force is to meet the safety demands in anappropriate way, as described in detail in the following. In order tosave on material and thus on costs, the thickness of the elements is tobe chosen to be as small as possible.

The thickness of the elements made of the fiber-reinforced compositematerial that are used can be reduced in particular in compositesaccording to the invention in which the elements have a rearreinforcement (also referred to as a backing), that is generally stuckon.

In particular, the elements and composites in accordance with theinvention are used as structural components. In this case they are usedfor armor plating, among other things, in the construction of vehiclesof both civil and military types including tanks, in automobileconstruction, in the construction of aircraft, for example ofhelicopters and airplanes, in shipbuilding and in the construction ofrailway vehicles. The armor plating of stationary objects such asbuildings and safes, for example, is also possible with the elements andcomposites in accordance with the invention, for example as a structuralcomponent. Furthermore, the elements and composites in accordance withthe invention can also be used in protective vests.

Even projectiles making impact during travel through space can, withappropriate construction of the elements and composites in accordancewith the invention, be absorbed by the latter so that a use for theprotection of spacecraft is also possible.

As a result of the use of the above-described elements and composites,it is possible, in particular, for a loading, for example by shellsplinters, by bombardment, for example by projectiles of any kind, to beabsorbed without the composite body cracking and exploding into aplurality of pieces. This behavior is completely surprising and couldnot have been expected, in particular because it was well knownheretofore that non-fiber-reinforced ceramic materials have a relativelybrittle behavior and thus, in the case of bombardment, a plate made ofthis ceramic material breaks up into a plurality of pieces. If theelements and the elements which have been reinforced on the rear sidehave a comparatively small thickness, a shot can pass through, althoughwithout a shattering or splintering occurring at the same time, that isunwanted in conventional ceramic materials.

Since the elements and composites in accordance with the invention donot shatter in the case of a point-focal load, they also offerprotection against multiple bombardment, in contrast to the knownceramic-based armor platings. The elements in accordance with theinvention that are made of reinforced composite materials with a ceramicmatrix can therefore be used as armor plating even with largerdimensions than the ceramics used until now. In contrast to the latter,the one-part elements and composites in accordance with the inventioncan have dimensions greater than 3 cm, preferably greater than 10 cm andparticularly preferably greater than 30 cm. Even larger dimensions arepossible for the elements so that, for example, portions of motorvehicles can be replaced by them as armor-plating protection.

Furthermore, the elements and composites in accordance with theinvention also display a very good behavior when bombarded withautomatic weapons (multi-hit properties), because the material is onlyweakened directly in the area of bombardment.

The fiber-reinforced composite material with a ceramic matrix of theelements in accordance with the invention is suitable for thesubstantial absorption of any impact-like load focussed at a point andcan therefore be used in the widest variety of ways in protectiontechnology. In particular, the use of the elements and composites in theform of armor plates, for example for automobiles, is of technicalinterest. Thus, for example, it is possible to produce body portions orbody reinforcements for airplanes, missiles, trains or even cars fromthis composite material and thus to obtain vehicles which are completelysecure against bombardment without their weight increasing too much.

It is likewise possible, as a result of the use of the fiber-reinforcedcomposite material, to line the floor region of a helicopter cockpit,for example.

A similar protection against bombardment can also be given to ships,which can be manufactured at least partially from this material.

It is likewise possible to use the fiber-reinforced composite materialfor the protection of buildings, bunkers and storage rooms, for examplefuel depots or personnel shelters (tented camps), as well astelecommunications systems or radar stations, without expensive or veryheavy materials having to be used for this purpose.

In accordance with the invention, it is, of course, also possible to usethe fiber-reinforced composite material as splinter or fragmentprotection, in particular as protection against grenade splinters orgrenade fragments. In this case, the thickness of a protective platemade of this composite material can even be made thinner than in thecase of the protection against projectiles.

The use of the fiber-reinforced composite material with a ceramic matrixalso includes protection in the civil field, for example in the form oflinings for protective vests or generally for clothing worn on the humanbody.

Furthermore, it is possible to obtain a protection for components ofspace stations, for example against meteorite impacts, as a result ofthe use described in accordance with the invention.

The fiber-reinforced composite materials used in accordance with theinvention are distinguished in particular as a result of the fact thatthe solid-body structure is retained for a very long time during energyimpact. The incident energy is then transformed inside the material.

Apart from this, the elements and composites used in accordance with theinvention are distinguished by a particularly low specific weight. Whileknown ceramic materials such as aluminum oxide have a relatively highspecific weight (the specific weight of aluminum oxide is 3.8 g/cm³),the composite materials used in accordance with the invention have aclearly lower specific weight of only 2.0 to 2.7 g/cm³, in particular2.3 to 2.4 g/cm³. This means that the composite materials used inaccordance with the invention in particular have a considerably lowerspecific weight than the metallic, ballistic steels used heretofore,which have a density of approximately 7.8 g/cm³. Their specific weight,however, is even lower than that of the known aluminum oxide ceramics.This makes possible a pronounced weight saving potential when thesematerials are used in vehicle construction, aircraft construction andshipbuilding as well as in the protection of people.

The composite bodies used in accordance with the invention aredistinguished by a very good breaking behavior, as may be observed inbombardment tests described below. The mechanical impulse energy of aprojectile that acts on the material is absorbed by way of internalenergy-absorbing effects in the composite body, inducing micro-cracks inthe regions of the matrix between the fibers, which gradually absorb theenergy of the bullets. In this connection, a flattening or mushroomingof the impacting projectiles results, in which case the bullet is brakedand a conversion of the kinetic energy into energy for crack formationtakes place.

In addition to carbon fibers and graphite fibers, technically equivalentfibers, such as aluminum oxide fibers, silicon nitride fibers andSi/B/C/N fibers, which are presented in German Patent DE 197 11 829 C1,for example, can also be used as the fibers. These can be contained inthe composite material of the elements and composites in accordance withthe invention in addition to or instead of the carbon fibers andgraphite fibers. Preferably, fibers based on silicon, carbon, boron,nitrogen, aluminum or mixtures thereof are used.

Basically, when selecting the fibers, the criterion that these fibersare high-temperature fibers and can thus withstand temperatures of up toapproximately 1600° C. should be fulfilled in order to ensure that theyare not quickly damaged upon infiltration with molten materials.Conventional materials have no fiber protection (shell) so that, forexample, unprotected carbon fibers are attacked upon infiltration withsilicon and it is impossible to obtain a ductile material. The fibersused in accordance with the invention therefore advantageously have aprotective coating. This preferably is formed of at least one carbonlayer or graphite layer which results from the coking of syntheticresins, for example, and/or other carbon-donating substances and wherepossible subsequent graphitizing. A plurality of protective layers madeof carbon or graphite is particularly preferred. The production of sucha fiber provided with a protective shell or shells is known from GermanPublished, Non-Prosecuted Patent Application DE 197 10 105 A1, forexample.

In addition to short fibers, fibers having a greater length can also beused in the composite materials of the elements according to theinvention. Basically, there is no restriction with respect to the fiberlength. If short fibers (fiber lengths of up to approximately 4 mm) andfibers of greater length are placed in the composite material, thelonger fibers above all contribute to the reinforcement of the material.The portion of these longer fibers is therefore denoted as reinforcingfibers in the following text and in the claims. In composite materialswhich contain only short fibers, these are the reinforcing fibers. Thebundle thickness of the fibers (actual fiber bundle) is usually 1,000 to920,000 filaments. The fibers of the elements in accordance with theinvention preferably have a bundle thickness of 1 to 3,000 filaments.

An organic polymer such as polyacrylonitrile or cellulose, for example,can even be used as a starting material for the fibers. Flat shapedbodies such as woven fabrics or nonwoven fabrics can be produced fromthat material, as described in German Published, Non-Prosecuted PatentApplication DE 195 17 911 A1. If cellulose is used, it is madeunmeltable in a pre-process. It is also possible to use inorganicpolymers, which are spun to form nonwoven fabrics. Polysilanes,polysilazanes, carbosilanes, which are made unmeltable, or nonwovenfabrics made of boron-containing silazanes, can be mentioned asmaterials to be used. It is favorable if woven fabrics are impregnatedwith substances of low viscosity, such as furfurylalcohol,polyphenylenes, polyimides or polyacrylates, in order to achieve a goodwetting.

The composite materials used in the elements in accordance with theinvention preferably also have phases of silicon and carbon in thematrix in addition to silicon carbide. It is particularly preferable ifthe matrix contains only phases of silicon carbide, silicon and carbon.

The composite material of the elements and composites in accordance withthe invention contains at least 10% by weight of silicon carbide,advantageously 20% by weight and particularly preferably 30% by weightwith respect to the total weight. The proportion of the fibers withrespect to the total weight should be at least 5% by weight, preferablyeven 10%, and particularly preferably the proportion of the fibers isabove 15% by weight. Furthermore, it is very advantageous if thecomposite material of the elements and composites in accordance with theinvention has a ductile breaking behavior.

In order to also use the elements and composites in accordance with theinvention as protection against the penetration of large caliberbullets, fiber-reinforced composite materials having the followingproperties are to be used.

A good protection is achieved if the composite material contains, withrespect to its total weight, 40 to 85% by weight, preferably 55 to 80%by weight and particularly preferably 65 to 75% by weight siliconcarbide, 5 to 55% by weight, preferably 10 to 40% by weight andparticularly preferably 15 to 25% by weight carbon (including fibers)and 0 to 30% by weight, preferably 2 to 20% by weight and particularlypreferably 5 to 15% by weight silicon. In this case, the proportion ofthe fibers with respect to the total weight is to be 5 to 40% by weight,preferably 8 to 30% by weight and particularly preferably 10 to 20% byweight. Furthermore, the average fiber length of the reinforcing fibersin this case is between 0.2 mm and 15 mm, preferably between 0.5 mm and5 mm and particularly preferably between 1 mm and 2 mm. Apart from this,the fibers are coated with at least one layer of carbon.

An element made of a composite material of this type prevents thepenetration of bullets having a kinetic energy of up to 942.9 J if theminimum thickness of the element parallel to the direction of impact ofthe bullet is 20 mm to 100 mm, preferably 24 mm to 60 mm andparticularly preferably 28 mm to 40 mm. It prevents the penetration ofbullets having a kinetic energy of up to 1510 J if the minimum thicknessof the element parallel to the direction of impact of the bullet is 25mm to 100 mm, preferably 28 mm to 70 mm and particularly preferably 36mm to 50 mm. Apart from this, it prevents the penetration of bulletshaving a kinetic energy up to 1805 J if the minimum thickness of theelement parallel to the direction of impact of the bullet is 32 mm to100 mm, preferably 36 mm to 80 mm and particularly preferably 40 mm to60 mm.

Furthermore, an element made of a composite material of this typeprevents the penetration of cone point-head bullets having a soft coremade of lead and a solid jacket made of steel with a mass of up to 10.2g and a bullet velocity of up to 430 m/s, if the minimum thickness ofthe element parallel to the direction of impact of the bullet is 20 mmto 100 mm, preferably 24 mm to 60 mm and particularly preferably 28 mmto 40 mm. It prevents the penetration of flat-headed bullets having asoft core made of lead and a solid jacket made of copper with a mass ofup to 15.6 g and a bullet velocity of up to 440 m/s if the minimumthickness of the element parallel to the direction of impact of thebullet is 25 mm to 100 mm, preferably 28 mm to 70 mm and particularlypreferably 36 mm to 50 mm. Apart from this, it prevents the penetrationof pointed bullets having a soft core made of lead with a steelpenetrator and a solid jacket made of copper with a mass of up to 4.0 gand a bullet velocity of up to 950 m/s if the minimum thickness of theelement parallel to the direction of impact of the bullet is 32 mm to100 mm, preferably 36 mm to 80 mm and particularly preferably 40 mm to60 mm.

A composite made up of an element made of such a composite material witha woven fabric of reinforcing fibers, which preferably has a thicknessof up to 15 mm, in which the element and the woven fabric are connectedto each other with an adhesive, prevents the penetration of bulletshaving a kinetic energy of up to 942.9 J, if the minimum thickness ofthe element parallel to the direction of impact of the bullet is 3.2 mmto 30 mm, preferably 4.5 mm to 25 mm and particularly preferably 6 mm to20 mm. It prevents the penetration of bullets having a kinetic energy ofup to 1510 J if the minimum thickness of the element parallel to thedirection of impact of the bullet is 4 mm to 40 mm, preferably 5.5 mm to30 mm and particularly preferably 7.5 mm to 25 mm. Apart from this, itprevents the penetration of bullets having a kinetic energy of up to1805 J if the minimum thickness of the element parallel to the directionof impact of the bullet is 4.8 mm to 50 mm, preferably 6 mm to 40 mm andparticularly preferably 8 mm to 30 mm. It prevents the penetration ofbullets having a kinetic energy of up to 2105 J if the minimum thicknessof the element parallel to the direction of impact of the bullet is 5.5mm to 50 mm, preferably 7 mm to 40 mm and particularly preferably 10 mmto 30 mm. It prevents the penetration of bullets having a kinetic energyof up to 3272 J if the minimum thickness of the element parallel to thedirection of impact of the bullet is 8 mm to 50 mm, preferably 10 mm to40 mm and particularly preferably 12 mm to 30 mm.

Furthermore, a composite made up of an element made of such a compositematerial with a woven fabric of reinforcing fibers, which preferably hasa thickness of up to 15 mm, in which the element and the woven fabricare connected to each other with an adhesive, prevents the penetrationof cone point-head bullets having a soft core made of lead and a solidjacket made of steel with a mass of up to 10.2 g and a bullet velocityof up to 430 m/s, if the minimum thickness of the element parallel tothe direction of impact of the bullet is 3.2 mm to 30 mm, preferably 4.5mm to 25 mm and particularly preferably 6 mm to 20 mm. It prevents thepenetration of flat-headed bullets having a soft core made of lead and asolid jacket made of copper with a mass of up to 15.6 g and a bulletvelocity of up to 440 m/s if the minimum thickness of the elementparallel to the direction of impact of the bullet is 4 mm to 40 mm,preferably 5.5 mm to 30 mm and particularly preferably 7.5 mm to 25 mm.Apart from this, it prevents the penetration of pointed bullets having asoft core made of lead with a steel penetrator and a solid jacket madeof copper with a mass of up to 4.0 g and a bullet velocity of up to 950m/s if the minimum thickness of the element parallel to the direction ofimpact of the bullet is 4.8 mm to 50 mm, preferably 6 mm to 40 mm andparticularly preferably 8 mm to 30 mm. It prevents the penetration ofcone point-head bullets having a soft core made of lead and a steelpenetrator and a solid jacket made of copper with a mass of up to 7.9 gand a bullet velocity of up to 730 m/s if the minimum thickness of theelement parallel to the direction of impact of the bullet is 5.5 mm to50 mm, preferably 7 mm to 40 mm and particularly preferably 10 mm to 30mm. It prevents the penetration of pointed bullets having a soft coremade of lead and a solid jacket made of steel with a mass of up to 9.5 gand a bullet velocity of up to 830 m/s if the minimum thickness of theelement parallel to the direction of impact of the bullet is 8 mm to 50mm, preferably 10 mm to 40 mm and particularly preferably 12 mm to 30mm.

A particularly good protection is achieved if the composite materialcontains, with respect to its total weight, 55 to 80% by weight andpreferably 65 to 75% by weight of silicon carbide, 10 to 40% by weightand preferably 15 to 25% by weight of carbon (including fibers) and 2 to20% by weight and preferably 5 to 15% by weight of silicon. In thiscase, the proportion of the fibers with respect to the total weight isto be 8 to 30% by weight and preferably 10 to 20% by weight.Furthermore, the average fiber length of the reinforcing fibers in thiscase is between 0.5 mm and 5 mm and preferably between 1 mm and 2 mm.Apart from this, the fibers are coated with at least one layer ofgraphitized carbon.

An element made of a composite material of this type prevents thepenetration of bullets having a kinetic energy of up to 942.9 J, if theminimum thickness of the element parallel to the direction of impact ofthe bullet is 15 mm to 100 mm, preferably 19 mm to 60 mm andparticularly preferably 23 mm to 40 mm. It prevents the penetration ofbullets having a kinetic energy of up to 1510 J if the minimum thicknessof the element parallel to the direction of impact of the bullet is 20mm to 100 mm, preferably 25 mm to 70 mm and particularly preferably 30mm to 50 mm. Apart from this, it prevents the penetration of bulletshaving a kinetic energy up to 1805 J if the minimum thickness of theelement parallel to the direction of impact of the bullet is 25 mm to100 mm, preferably 31 mm to 80 mm and particularly preferably 37 mm to60 mm.

Furthermore, an element made of a composite material of this typeprevents the penetration of cone point-head bullets having a soft coremade of lead and a solid jacket made of steel with a mass of up to 10.2g and a bullet velocity of up to 430 m/s, if the minimum thickness ofthe element parallel to the direction of impact of the bullet is 15 mmto 100 mm, preferably 19 mm to 60 mm and particularly preferably 23 mmto 40 mm. It prevents the penetration of flat-headed bullets having asoft core made of lead and a solid jacket made of copper with a mass ofup to 15.6 g and a bullet velocity of up to 440 m/s if the minimumthickness of the element parallel to the direction of impact of thebullet is 20 mm to 100 mm, preferably 25 mm to 70 mm and particularlypreferably 30 mm to 50 mm. Apart from this, it prevents the penetrationof pointed bullets having a soft core made of lead with a steelpenetrator and a solid jacket made of copper with a mass of up to 4.0 gand a bullet velocity of up to 950 m/s, if the minimum thickness of theelement parallel to the direction of impact of the bullet is 25 mm to100 mm, preferably 31 mm to 80 mm and particularly preferably 37 mm to60 mm. A composite made up of an element made of such a compositematerial with a woven fabric of reinforcing fibers, which preferably hasa thickness of up to 15 mm, in which the element and the woven fabricare connected to each other with an adhesive, prevents the penetrationof bullets having a kinetic energy of up to 942.9 J if the minimumthickness of the element parallel to the direction of impact of thebullet is 2.4 mm to 30 mm, preferably 3.5 mm to 25 mm and particularlypreferably 5 mm to 20 mm. It prevents the penetration of bullets havinga kinetic energy of up to 1510 J if the minimum thickness of the elementparallel to the direction of impact of the bullet is 3 mm to 40 mm,preferably 4.5 mm to 30 mm and particularly preferably 6.5 mm to 25 mm.Apart from this, it prevents the penetration of bullets having a kineticenergy of up to 1805 J if the minimum thickness of the element parallelto the direction of impact of the bullet is 3.6 mm to 50 mm, preferably5 mm to 40 mm and particularly preferably 7 mm to 30 mm. It prevents thepenetration of bullets having a kinetic energy of up to 2105 J if theminimum thickness of the element parallel to the direction of impact ofthe bullet is 4 mm to 50 mm, preferably 6 mm to 40 mm and particularlypreferably 8 mm to 30 mm. It prevents the penetration of bullets havinga kinetic energy of up to 3272 J if the minimum thickness of the elementparallel to the direction of impact of the bullet is 6 mm to 50 mm,preferably 7.5 mm to 40 mm and particularly preferably 9 mm to 30 mm.Furthermore, a composite made up of an element made of such a compositematerial with a woven fabric of reinforcing fibers, which preferably hasa thickness of up to 15 mm, in which the element and the woven fabricare connected to each other with an adhesive, prevents the penetrationof cone point-head bullets having a soft core made of lead and a solidjacket made of steel with a mass of up to 10.2 g and a bullet velocityof up to 430 m/s, if the minimum thickness of the element parallel tothe direction of impact of the bullet is 2.4 mm to 30 mm, preferably 3.5mm to 25 mm and particularly preferably 5 mm to 20 mm. It prevents thepenetration of flat-headed bullets having a soft core made of lead and asolid jacket made of copper with a mass of up to 15.6 g and a bulletvelocity of up to 440 m/s, if the minimum thickness of the elementparallel to the direction of impact of the bullet is 3 mm to 40 mm,preferably 4.5 mm to 30 mm and particularly preferably 6.5 mm to 25 mm.Apart from this, it prevents the penetration of pointed bullets having asoft core made of lead with a steel penetrator and a solid jacket madeof copper with a mass of up to 4.0 g and a bullet velocity of up to 950m/s, if the minimum thickness of the element parallel to the directionof impact of the bullet is 3.6 mm to 50 mm, preferably 5 mm to 40 mm andparticularly preferably 7 mm to 30 mm. It prevents the penetration ofcone point-head bullets having a soft core made of lead and a steelpenetrator and a solid jacket made of copper with a mass of up to 7.9 gand a bullet velocity of up to 730 m/s, if the minimum thickness of theelement parallel to the direction of impact of the bullet is 4 mm to 50mm, preferably 6 mm to 40 mm and particularly preferably 8 mm to 30 mm.It prevents the penetration of pointed bullets having a soft core madeof lead and a solid jacket made of steel with a mass of up to 9.5 g anda bullet velocity of up to 830 m/s, if the minimum thickness of theelement parallel to the direction of impact of the bullet is 6 mm to 50mm, preferably 7.5 mm to 40 mm and particularly preferably 9 mm to 30mm.

A extremely good protection is achieved if the composite materialcontains, with respect to its total weight, 65 to 75% by weight siliconcarbide, 15 to 25% by weight carbon (including fibers) and 5 to 15% byweight silicon. In this case, the proportion of the fibers with respectto the total weight is to be 10 to 20% by weight. Furthermore, theaverage fiber length of the reinforcing fibers in this case is between 1mm and 2 mm. Apart from this, the fibers are coated with at least threelayers of graphitized carbon.

An element made of a composite material of this type prevents thepenetration of bullets having a kinetic energy of up to 942.9 J if theminimum thickness of the element parallel to the direction of impact ofthe bullet is 12 mm to 100 mm, preferably 15 mm to 60 mm andparticularly preferably 18 mm to 40 mm. It prevents the penetration ofbullets having a kinetic energy of up to 1510 J if the minimum thicknessof the element parallel to the direction of impact of the bullet is 16mm to 100 mm, preferably 20 mm to 70 mm and particularly preferably 24mm to 50 mm. Apart from this, it prevents the penetration of bulletshaving a kinetic energy up to 1805 J if the minimum thickness of theelement parallel to the direction of impact of the bullet is 20 mm to100 mm, preferably 24 mm to 80 mm and particularly preferably 28 mm to60 mm.

Furthermore, an element made of a composite material of this typeprevents the penetration of cone point-head bullets having a soft coremade of lead and a solid jacket made of steel with a mass of up to 10.2g and a bullet velocity of up to 430 m/s, if the minimum thickness ofthe element parallel to the direction of impact of the bullet is 12 mmto 100 mm, preferably 15 mm to 60 mm and particularly preferably 18 mmto 40 mm. It prevents the penetration of flat-headed bullets having asoft core made of lead and a solid jacket made of copper with a mass ofup to 15.6 g and a bullet velocity of up to 440 m/s, if the minimumthickness of the element parallel to the direction of impact of thebullet is 16 mm to 100 mm, preferably 20 mm to 70 mm and particularlypreferably 24 mm to 50 mm. Apart from this, it prevents the penetrationof pointed bullets having a soft core made of lead with a steelpenetrator and a solid jacket made of copper with a mass of up to 4.0 gand a bullet velocity of up to 950 m/s, if the minimum thickness of theelement parallel to the direction of impact of the bullet is 20 mm to100 mm, preferably 24 mm to 80 mm and particularly preferably 28 mm to60 mm.

A composite made up of an element made of such a composite material witha woven fabric of reinforcing fibers, which preferably has a thicknessof up to 15 mm, in which the element and the woven fabric are connectedto each other with an adhesive, prevents the penetration of bulletshaving a kinetic energy of up to 942.9 J if the minimum thickness of theelement parallel to the direction of impact of the bullet is 2 mm to 30mm, preferably 2.5 mm to 25 mm and particularly preferably 4 mm to 20mm. It prevents the penetration of bullets having a kinetic energy of upto 1510 J if the minimum thickness of the element parallel to thedirection of impact of the bullet is 2.5 mm to 40 mm, preferably 3 mm to30 mm and particularly preferably 5.5 mm to 25 mm. Apart from this, itprevents the penetration of bullets having a kinetic energy of up to1805 J if the minimum thickness of the element parallel to the directionof impact of the bullet is 3 mm to 50 mm, preferably 4 mm to 40 mm andparticularly preferably 6 mm to 30 mm. It prevents the penetration ofbullets having a kinetic energy of up to 2105 J if the minimum thicknessof the element parallel to the direction of impact of the bullet is 3.5mm to 50 mm, preferably 4.5 mm to 40 mm and particularly preferably 7 mmto 30 mm. It prevents the penetration of bullets having a kinetic energyof up to 3272 J if the minimum thickness of the element parallel to thedirection of impact of the bullet is 5 mm to 50 mm, preferably 6 mm to40 mm and particularly preferably 8 mm to 30 mm.

Furthermore, a composite made up of an element made of such a compositematerial with a woven fabric of reinforcing fibers, which preferably hasa thickness of up to 15 mm, in which the element and the woven fabricare connected to each other with an adhesive, prevents the penetrationof cone point-head bullets having a soft core made of lead and a solidjacket made of steel with a mass of up to 10.2 g and a bullet velocityof up to 430 m/s, if the minimum thickness of the element parallel tothe direction of impact of the bullet is 2 mm to 30 mm, preferably 2.5mm to 25 mm and particularly preferably 4 mm to 20 mm. It prevents thepenetration of flat-headed bullets having a soft core made of lead and asolid jacket made of copper with a mass of up to 15.6 g and a bulletvelocity of up to 440 m/s, if the minimum thickness of the elementparallel to the direction of impact of the bullet is 2.5 mm to 40 mm,preferably 3 mm to 30 mm and particularly preferably 5.5 mm to 25 mm.Apart from this, it prevents the penetration of pointed bullets having asoft core made of lead with a steel penetrator and a solid jacket madeof copper with a mass of up to 4.0 g and a bullet velocity of up to 950m/s, if the minimum thickness of the element parallel to the directionof impact of the bullet is 3 mm to 50 mm, preferably 4 mm to 40 mm andparticularly preferably 6 mm to 30 mm. It prevents the penetration ofcone point-head bullets having a soft core made of lead and a steelpenetrator and a solid jacket made of copper with a mass of up to 7.9 gand a bullet velocity of up to 730 m/s, if the minimum thickness of theelement parallel to the direction of impact of the bullet is 3.5 mm to50 mm, preferably 4.5 mm to 40 mm and particularly preferably 7 mm to 30mm. It prevents the penetration of pointed bullets having a soft coremade of lead and a solid jacket made of steel with a mass of up to 9.5 gand a bullet velocity of up to 830 m/s, if the minimum thickness of theelement parallel to the direction of impact of the bullet is 5 mm to 50mm, preferably 6 mm to 40 mm and particularly preferably 8 mm to 30 mm.

In addition to the fibers, various fillers can also be placed in thematrix. In particular, silicides, carbides, borides, metals and carbon,for example in the form of carbon black, graphite, coke or mixturesthereof, are suitable as fillers. Silicon carbides, B₄C, carbon black,graphite or zirconium borides are of particular interest in this case.The use of carbon black and/or graphite is particularly preferredbecause a good conversion into SiC is rendered possible by thesesubstances. The use of B₄C is common in applications at the present timeif a high level of hardness of the composite body is to be achieved.Zirconium borides are used because of their resistance to hightemperatures. Therefore, advantages are to be expected when they areused for the composite bodies used in accordance with the invention, inparticular in the case of bombardment with signal ammunition. If,however, composite bodies having a particularly low specific weight areto be used, it is preferable to use fillers other than zirconium boride,which has a high density.

The amount of the fillers to be used if appropriate can be determined asa function of the properties of the composite body that are to beachieved. When reacting fillers such as carbon black or graphite areused, the amount is preferably up to 40% by weight, with respect to themixture at the beginning of the production. At higher amounts, adeformation of the body or even cracking can occur. More preferably, theamount is up to 30% by weight. If non-reacting fillers, for example SiC,are used, even higher concentrations are usable. The proportion of suchfillers depends fundamentally on the brittleness and the hardness whichare to be adjusted.

A significant advantage of the use of the fiber-reinforced compositematerial with a ceramic matrix lies in the fact that the elements can beproduced directly in the shape of the desired structural component, sothat shaping steps after the production of the elements can be avoidedand thus a further reduction in costs in the production of protectiveplates or armor plates, for example, is obtained. In view of the highbreaking strength of the elements, it is not absolutely necessary toprovide the elements in accordance with the invention with a rear-sidereinforcement. In that case the reinforcing material, such as fiberfabric (for example aramide fibers) or metal plates, is glued on to therear side of the composite material in order to obtain abombardment-resistant armor plate. Instead, the composite body itselfcan already form this armor plate. However, the thickness of an elementin accordance with the invention that is made of a composite material isgreater than that required for the element if, as a result of therear-side reinforcement, a composite in accordance with the inventionhaving the same effect is made available.

The production of the composite material which is fiber-reinforced atleast partly with carbon fibers and/or graphite fibers and has a ceramicmatrix which contains silicon carbide can, for example, take placeaccording to the processes known from German Patent DE 197 11 829 C1 orGerman Published, Non-Prosecuted Patent Application DE 197 10 105 A1.Reference to those two printed publications is made explicitly withrespect to the production process.

Basically, all known processes can be used in order to producefiber-reinforced C/SiC ceramics. In the processes cited above, thefollowing production steps are carried out in order to produce compositematerials into which individual fibers (or fiber bundles) areincorporated.

As described in German Patent DE 197 11 829 C1 and German Published,Non-Prosecuted Patent Application DE 197 10 105 A1, for example, theincorporated fibers are pre-treated or produced and mixed, by way of amixer, with a carbon-donating resin and are molded into the initialshape by way of a pressing mold and hardened at temperatures of up toapproximately 150° C. The molded bodies (CFC precursors) which result inthis way are pyrolyzed at temperatures of up to approximately 1,000° C.and possibly subsequently graphitized at temperatures of up toapproximately 2,000° C.

The CFC preliminary body which is obtained in this way is subsequentlyimpregnated with liquid silicon at temperatures of up to approximately1800° C. in a vacuum. In this connection, a large portion of the matrixcarbon reacts in an exothermal reaction with the incorporated silicon toform silicon carbide. Due to a special pre-treatment of the fibers, thecarbon fibers are retained during this reaction and can thus contributeto the ductilization of the ceramics.

Known 2D and 3D CFC woven-fabric structures with large volumetriccontents of the fibers, which are also suitable, can be produced, interalia, directly from polyacrylonitrile planar fiber structures by way ofthe direct oxidation process and by subsequent pyrolysis. In thisconnection, the following process steps are carried out in particular.

The carbon-fiber reinforcing structure is made into a shape whichcorresponds to the desired final shape. The fiber body is impregnatedunder pressure with a resin matrix in a vacuum at 130° C., and afterhardening and removal from the mold, finished according to need.

CFK preliminary bodies which result in this way are then pyrolyzed attemperatures of up to 1000° C. Then, an increase of the density of thisCFC material can take place with a pitch-based or resin-basedcarbon-containing polymer in one or more steps, with a further pyrolysisstep following each density-increasing step. In this way, a CFC materialwhich is suitable for the subsequent infiltration is obtained. In thatmaterial the carbon fibers are sufficiently protected against an attackof the liquid silicon in particular. Subsequently, a graphitization ofthe CFC composite material at temperatures of up to approximately 2000°C. can take place.

The silication is carried out at temperatures of up to approximately1800° C. in a vacuum.

For example, the shapes of vehicle doors or certain aircraft componentscan be formed directly by way of the concrete processes described above.

In addition to silicon, other materials also come into consideration asan infiltration material and those materials are added to the silicon.Basically, the materials used for infiltration must be able to melt inthe temperature range up to 1800° C. Aluminum, boron, magnesium,nitrogen, carbon and compounds or mixtures thereof as well as silicidescome into consideration as further infiltration materials. Evensilicides exclusively can be infiltrated in order to form a matrixcontaining silicon carbide.

Silicon is particularly preferably used as an infiltration materialduring the production of the composite bodies. During the addition ofother substances, silicides, such as, for example, molybdenum silicides,iron silicides, chromium silicides, tantalum silicides or mixtures, arepreferably added to silicon. Materials of this type can alter themelting point of the infiltration material.

It is likewise also possible to use silicon-based polymers as aninfiltration material. Examples of such polymers are, for example,boron-containing polysilazanes.

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is described herein as embodied in armoredproducts made of a fiber-reinforced composite material with a ceramicmatrix, it is nevertheless not intended to be limited to the detailsgiven, since various modifications and structural changes may be madetherein without departing from the spirit of the invention and withinthe scope and range of equivalents of the claims.

The construction of the invention, however, together with additionalobjects and advantages thereof will be best understood from thefollowing description of specific embodiments when read in connectionwith the accompanying examples.

DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLES 1 AND 2

Production of Elements Made of a Fiber-Reinforced Composite Materialwith a Ceramic Matrix.

First of all, a prepreg is produced from 3K carbon fiber bundles (3,000individual filaments). The carbon fibers were produced on the basis ofPAN fibers. For this purpose, the fiber bundles were interlaced to forma Koeper-fabric, the woven fabric was subsequently soaked in phenolicresin (resol type) and it was provided with an anti-adhesive paper onboth sides. After this, the resin-soaked woven fabric was heated to 130°C. in order to achieve the adhesiveness of the prepreg.

Subsequently, the prepreg plates were laid on top of each other andpressed to form a pressed body. This was then baked at 900° C., with abaking curve having a rise of 5° C. per minute in a range between 400°C. and 600° C. Then, three times, one after another, the CFC body thatwas obtained in this way was first impregnated with a coal tar pitchhaving a softening point of 60° C. and then baked, again at 900° C., inorder to compact it further.

The CFC body which was obtained in this way was then first broken upinto small pieces in a jaw breaker (manufacturer: Alpine Hosokawa) andsubsequently cut into fiber bundles in a cutting mill (manufacturer:Alpine Hosokawa). The fiber bundles were then sorted in a tumblersieving unit (manufacturer: Allgaier) into individual fiber fractions,with sieve inserts (sieving area 1.15 m²) having a clear mesh apertureof 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm and 6 mm in accordance with ISO 9044.As a result of this sieving process, different fiber fractions wereobtained, as a result of which there were, among others, a fraction Awith fibers of a length of 12.45 mm to 17.55 mm and a width of 660 μm to2.26 mm, a fraction B with fibers of a length of 8.5 mm to 13.5 mm and awidth of 690 μm to 2.21 mm, a fraction C with fibers of a length of 5.5mm to 10.5 mm and a width of 760 μm to 2.16 mm, a fraction D with fibersof a length of 0.2 mm to 3 mm and a width of 200 μm to 1 mm, a fractionE with fibers of a length of 0.1 mm to 3 mm and a width of 50 to 500 μmand a fraction F with fibers of a length up to 0.3 mm and a width of 8to 200 μm.

Subsequently, for samples of Example 1, a mixture 1 made up of 70% ofthe total weight of fibers, in accordance with a composition: 35%fraction D, 35% fraction E and 30% fraction F, and 30% of the totalweight of phenolic resin (resol type) as a binding agent, and forsamples of Example 2, a mixture 2 made up of 70% of the total weight offibers, in accordance with a composition: 12% fraction A, 18% fractionB, 40% fraction C and 30% fraction D, and 21% of the total weight ofphenolic resin (resol type) and 9% of the total weight of coal tar pitch(softening point: 230° C.) as a binding agent, were produced in a Z-armkneader (manufacturer: Werner & Pfleiderer) by mixing for 15 minutes ata rotational speed of 30 l/min. Subsequently, in each case 1200 g of themixture 1 was pressed in a stamping press in a square pressing moldhaving a side length of 325 mm at a specific pressure of 12 Kp/cm² and atemperature of 130° C. This temperature was maintained for 3 hours at aconstant mold pressure. After cooling to 30° C., the hardened plate wasremoved from the pressing mold. As a result of this manner ofproceeding, a CFK plate with a height (thickness) of 10 mm and a densityof 1.2 g/cm³ was obtained.

In an analogous manner, plates with a thickness of 38 mm and a densityof 1.18 g/cm³ were obtained in each case from 5100 g of the mixture 2.

After this, the carbonization of the samples took place at 900° C. underinert gas (heating rate of 2 K/min). The cooling of the plates to roomtemperature took place in an uncontrolled manner at up to 10 K/min.After carbonization, these plates had densities of 1.05 g/cm³(Example 1) and 1.03 g/cm³ (Example 2).

Subsequently, the infiltration of the samples at 1700° C. with liquidsilicon took place in a vacuum in a high-temperature furnace with asilicon supply (particle size up to 5 mm) of one and a half times thesample weight, as a result of which the SiC structure of the matrix ofthe samples was generated. In this connection, the silication took placefirst of all with a temperature rise of 10 K/min to 1400° C. and then 5K/min to 1800° C. The temperature was then held for 45 minutes, then atemperature drop with 5 K/min to 1400° C. and subsequently anuncontrolled cooling, took place. The C/SiC composite materials thatwere obtained in this way had densities of 2.4 g/cm³ and 2.35 g/cm³. Theplates made of the C/SiC composite material of Example 1 that wereproduced in this way had a fiber proportion with respect to the totalweight of 15% and a composition with respect to the total weight of 68%silicon carbide, 22% carbon and 10% silicon. The average fiber lengthwas 1.5 mm. The plates made of the C/SiC composite material of Example 2had a fiber proportion with respect to the total weight of 17% and acomposition with respect to the total weight of 58% silicon carbide, 31%carbon and 11% silicon. The average fiber length of the reinforcingfibers was 10 mm.

EXAMPLE 3

Production of an Element Made of a Fiber-Reinforced Composite Materialwith a Ceramic Matrix having a Rear-Side Reinforcement.

The 10 mm thick plates produced in accordance with Example 1 wereadditionally provided with a conventional rear-side reinforcement system(backing) in order to use them for protection against bombardment. Inorder to do so, the rear side of the ceramic plate was first blastedwith silica sand and after that 10 layers of aramide fiber fabric T 750(Akzo Nobel, Germany) were glued to the rear side of the C/SiC platewith a PUR glue SIKAFLEX 225 FC (manufacturer: Sika Chemie GmbH,Germany) and an adhesive primer.

Results of Bombardment Tests:

Bombardment tests were carried out with the elements made offiber-reinforced composite materials having a ceramic matrix with arear-side reinforcement in accordance with Example 3 and without arear-side reinforcement in accordance with Example 2. The testingprocess took place in a penetration test according to the Euro standard,DIN EN 1523. The test requirements were the impeding of penetration inresistance classes according to Table 1 of the Euro standard DIN EN1522. In order to set up the test, the plates were clamped on a stand,with the test sample being fastened at an angle of 90° to the shootingdirection. The firing distance was 5 or 10 m. The striking distance was120 mm±10 mm.

First, bombardment tests were carried out on plates having thedimensions 325 mm×278 mm×38 mm which were produced from plates inaccordance with Example 2. It was found that the plates resisted thefollowing bombardment tests, with at least three shots being fired at aplate in each case.

Test 1 (Bombardment Class FB 3):

A weapon type “test barrel” with a 357 magnum caliber was used as theweapon, and the bullet had a solid jacket made of steel, a conepoint-head and a soft core made of lead. The bullet weight was 10.2 g.The test distance was 5 m. The bullet velocity was 430 m/s and thebullet energy was 942.9 J.

Test 2 (Bombardment Class FB 4):

A weapon type “test barrel” with a 44 Rem. magnum caliber was used asthe weapon, and the bullet had a solid jacket made of copper, aflat-head and a soft core made of lead. The bullet weight was 15.6 g.The test distance was 5 m. The bullet velocity was 440 m/s and thebullet energy was 1510 J.

It became clear that the plates in the case of this test are alsoresistant to a multiple bombardment if the bullets hit with a spacing of50 mm, which corresponds to the effect of automatic weapons (multi-hitcapability).

Test 3 (Bombardment Class FB 5):

A weapon type “test barrel” with a 5.56 mm×45 mm caliber was used as theweapon, and the bullet had a solid jacket made of copper, a pointed headand a soft core made of lead with a steel penetrator (type SS 109). Thebullet weight was 4.0 g. The test distance was 10 m. The bullet velocitywas 950 m/s and the bullet energy was 1805 J.

In all of these bombardment tests on the large-sized protective elementsmade of the C/SiC composite material, no crack preventing a further useas protection appeared in the elements.

Apart from this, elements having the dimensions 300 mm×300 mm inaccordance with Example 3, which had a C/SiC composite-material plate ofonly 10 mm thickness and a rear-side reinforcement, were exposed to thebombardment tests.

Test 4 (Bombardment Class FB 3):

A weapon type “test barrel” with a 357 magnum caliber was used as theweapon, and the bullet had a solid jacket made of steel, a conepoint-head and a soft core made of lead. The bullet weight was 10.2 g.The test distance was 5 m. The bullet velocity was 430 m/s and thebullet energy was 942.9 J.

Test 5 (Bombardment Class FB 4):

A weapon type “test barrel” with a 44 Rem. magnum caliber was used asthe weapon, and the bullet had a solid jacket made of copper, aflat-head and a soft core made of lead. The bullet weight was 15.6 g.The test distance was 5 m. The bullet velocity was 440 m/s and thebullet energy was 1510 J.

It became clear that the plates in the case of this test are alsoresistant to a multiple bombardment if the bullets hit with a spacing of50 mm, which corresponds to the effect of automatic weapons (multi-hitcapability).

Test 6 (Bombardment Class FB 4+):

A Kalashnikov AK 47 with a 7.62 mm×39 mm caliber was used as the weapon,and the bullet had a solid jacket made of copper, a cone point-head anda soft core made of lead with a steel penetrator. The bullet weight was7.9 g. The test distance was 10 m. The bullet velocity was 730 m/s andthe bullet energy was 2105 J.

Test 7 (Bombardment Class FB 5):

A weapon type “test barrel” with a 5.56 mm×45 mm caliber was used as theweapon, and the bullet had a solid jacket made of copper, a pointed headand a soft core made of lead with a steel penetrator (type SS 109). Thebullet weight was 4.0 g. The test distance was 10 m. The bullet velocitywas 950 m/s and the bullet energy was 1805 J.

Test 8 (Bombardment Class FB 6):

A weapon type “test barrel” with a 7.62 mm×51 mm caliber was used as theweapon, and the bullet had a solid jacket made of steel, a pointed headand a soft core made of lead. The bullet weight was 9.5 g. The testdistance was 10 m. The bullet velocity was 830 m/s and the bullet energywas 3272 J.

No crack preventing a further use as protection appeared in the elementseven in these bombardment tests on the large-sized protective elementsmade of the C/SiC composite material with rear-side reinforcement.

The prevailing temperature in the bombardment tests was 20 to 22° C.

On the basis of the above results, it is evident that elements made ofC/SiC composite materials with and without rear reinforcement can bebombarded without shattering. In this connection, the plates display aresistance even in the case of high demands. In particular, thethickness of the C/SiC plates in the case of a rear-side reinforcementaccording to conventional technology can be chosen to be so small thatan economical use is also provided and despite this a high level ofsafety is ensured.

We claim:
 1. An armor plate, comprising: a body having at least onedimension at least equal to 3 cm, in a direction perpendicular to a loadto be absorbed; said body including a fiber-reinforced compositematerial, said composite material having reinforcing fibers and aceramic matrix being obtained by pyrolysis of molded bodies attemperatures of up to approximately 1000° C. and impregnation withsilicon at temperatures of up to approximately 1800° C. with at least10% by weight of silicon carbide, said ceramic matrix having phasesselected from the group consisting of phases of carbon, and phases ofcarbon and phases of silicon; and at least 5% by weight of saidreinforcing fibers selected from the group consisting of carbon fibers,graphite fibers, and carbon fibers and graphite fibers.
 2. The armorplate according to claim 1, wherein said at least one dimension is atleast equal to 30 cm.
 3. The armor plate according to claim 1, whereinsaid ceramic matrix of said composite material consists of phasesselected from the group consisting of phases of carbon; phases of carbonand silicon; phases of silicon carbide and carbon; and phases ofsilicon, silicon carbide, and carbon.
 4. The armor plate according toclaim 1, wherein said fiber-reinforced composite material has a totalweight, and a proportion of said reinforcing fibers with respect to saidtotal weight is at least 5% by weight.
 5. The armor plate according toclaim 1, wherein said fiber-reinforced composite material has a totalweight, and a proportion of said reinforcing fibers with respect to saidtotal weight is at least 15% by weight.
 6. The armor plate according toclaim 1, wherein said reinforcing fibers include fibers selected fromthe group consisting of aluminum oxide fibers, silicon nitride fibers,and Si/B/C/N fibers.
 7. The armor plate according to claim 1, whereinsaid composite material has a ductile breaking behavior.
 8. The armorplate according to claim 5, wherein said composite material has aductile breaking behavior.
 9. The armor plate according to claim 1,wherein said reinforcing fibers have a coating.
 10. The armor plateaccording to claim 9, wherein said coating is selected from the groupconsisting of at least one layer of carbon, at least one layer ofgraphite, and layers of carbon and graphite.
 11. The armor plateaccording to claim 1, wherein each of said reinforcing fibers issurrounded by and connected to a shell of graphite converted partiallyinto silicon carbide, said graphite resulting from coking and subsequentgraphitizing of at least one material selected from the group consistingof synthetic resins, other carbon-donating substances, and syntheticresins and other carbon-donating substances.
 12. The armor plateaccording to claim 1, wherein said body has a shaped structure.
 13. Thearmor plate according to claim 10, wherein said body has a shapedstructure.
 14. The armor plate according to claim 1, wherein saidcomposite material contains at least 5 percent of carbon other than inthe form of reinforcing fibers, with respect to its total weight.
 15. Anarmor plate, comprising: a composite material having reinforcing fibersand a total weight, said composite material including: a ceramic matrixwith at least 10% by weight of silicon carbide, and phases selected fromthe group consisting of phases of carbon, and phases of carbon andphases of silicon being obtained by pyrolysis of molded bodies attemperatures of up to approximately 1000° C. and impregnation withsilicon at temperatures of up to approximately 1800° C.; and saidreinforcing fibers having a proportion of at least 5% by weight withrespect to said total weight and being selected from the groupconsisting of carbon fibers, graphite fibers, and carbon fibers andgraphite fibers.
 16. The armor plate according to claim 15, wherein saidcomposite material has at least one dimension at least equal to 3 cm, ina direction perpendicular to a load to be absorbed.
 17. The armor plateaccording to claim 15, wherein said ceramic matrix of said compositematerial consists of phases selected from the group consisting of phasesof carbon; phases of carbon and silicon; phases of silicon carbide andcarbon; and phases of silicon, silicon carbide, and carbon.
 18. Thearmor plate according to claim 15, wherein said reinforcing fibershaving a proportion of at least 15% by weight with respect to the totalweight.
 19. The armor plate according to claim 15, wherein saidreinforcing fibers include fibers selected from the group consisting ofaluminum oxide fibers, silicon nitride fibers, and Si/B/C/N fibers. 20.The armor plate according to claim 15, wherein said composite materialhas a ductile breaking behavior.
 21. The armor plate according to claim15, wherein said composite material contains at least 5 percent ofcarbon other than in the form of reinforcing fibers, with respect tosaid total weight.
 22. The armor plate according to claim 15, wherein atleast 5% by weight of said reinforcing fibers are selected from thegroup consisting of carbon fibers, graphite fibers, and carbon fibersand graphite fibers.
 23. The armor plate according to claim 15, whereinsaid reinforcing fibers have a coating.
 24. The armor plate according toclaim 23, wherein said coating is selected from the group consisting ofat least one layer of carbon, at least one layer of graphite, and layersof carbon and graphite.
 25. The armor plate according to claim 15,wherein each of said reinforcing fibers is surrounded by and connectedto a shell of graphite converted partially into silicon carbide, saidgraphite resulting from coking and subsequent graphitizing of at leastone material selected from the group consisting of synthetic resins,other carbon-donating substances, and synthetic resins and othercarbon-donating substances.
 26. The armor plate according to claim 15,wherein said body has a shaped structure.